1. Field of the Invention
This invention relates to air diffusers of the type used in connection with air conditioning cooling and heating equipment.
2. Description of the Prior Art
Early air conditioning equipment delivered cooled air to a space to be cooled, but no attempt was made to enhance the diffusion of the cooled air throughout the space. Instead, it was believed that the natural cycle of cool air falling and warm air rising would be adequate to cool a space in an acceptable period of time.
Those skilled in the art of fluid dynamics observed, however, that substantial amounts of energy could be saved if the natural circulation of the air were enhanced by air diffusing equipment. As air diffusing equipment came into use, a performance index known as the air diffusion performance index was created to measure the efficiency of such equipment. As the air diffusion performance index of an air injection unit goes up, the comfort and indoor air quality produced in the conditioned space is improved.
It was eventually discovered that if the cooled air were formed into a fast flowing narrow stream of air, ambient air would be entrained into that fast flowing stream and air circulation within the space to be cooled would be enhanced. An example of that technology is disclosed in U.S. Pat. No. 4,876,949 to Fairchild et. al. A hollow housing having sidewalls is suspended from a ceiling, and rows of circular openings are formed in the sidewalls so that a stream of air can escape from each opening. The sidewalls are oblique to a vertical plane so that each stream of air is directed downwardly into the space to be cooled.
Although the Fairchild et. al. approach enhances air circulation and thus performs its intended function, it does have a few drawbacks. The housing is somewhat expensive because it requires a large amount of material. Moreover, although ambient air is entrained into the cylindrical streams of air flowing from the circular openings, the amount of entrainment is not optimal. The amount of entrainment is not optimal for two reasons. First of all, the angle at which the columns of air are injected is not optimal. Moreover, the cylindrical or columnar shape of the injected air is also not optimal. Thus, the air diffusion performance index of the Fairchild system is not optimal.
Despite these drawbacks, air injectors of the Fairchild et. al. type remain attractive because of the substantial energy savings they provide. The columns of air injected into the space, due to their rapid movement and the concomitant entrainment of air into their respective wakes, may be of low volumetric extent, i.e., a small amount of fast moving cold air can lower the temperature of a space more efficiently than a slower moving volume of warmer air having a greater volumetric extent. Larger fans, coils, filters, ducts, and other related equipment are required to produce larger volumes of cool air, of course. Thus, if a space can be cooled with less cool air, then substantial savings can be realized. Smaller fans, coils, filters, ducts, and related equipment cost less to manufacture and cost less to operate since they consume smaller quantities of energy.
What is needed, then, is a diffuser that uses less material in its construction, and that entrains greater amounts of air. Specifically, the art awaits development of a diffuser having a substantially enhanced air diffusion performance index so that even greater energy savings can be realized while maintaining higher indoor air quality.
At the time the present invention was made, the prior art, considered as a whole in accordance with the requirements of law, neither taught nor suggested to those of ordinary skill in the diffuser arts how the desired objectives could be obtained.